ILC Start-End Simulations

1. ILC Start-End Simulations Glen White, SLAC May 13, 2014 AWLC14, Fermilab

2. ILC Start-End Simulations • Form list of all expected “error” sources and generate N (typically ~100) random machine “seeds” • e.g. magnetic errors, misalignments • e.g. dynamic errors: ground motion + feedbacks • e.g. realistic diagnostics performance (BPM scale errors, resolutions…) • Apply all commissioning, tuning and operational measures in as realistic manner as possible using expected input devices with expected performances. • Examine ensemble of results, get a probabilistic picture of what the running state of the entire machine is. • Especially luminosity.

3. Why? • Accurate picture of expected luminosity performance of the machine. • Tuning is a part of the lattice description. • Solid basis for forming tolerance specifications. • Accurately evaluate impact of design changes and choices. • Stored results and infrastructure can form the input of other studies • Limitations: • Doesn’t cover cases where machine is “broken”, still need to consider capability to diagnose faults.

4. What to include? • DR? • Historically not included, usually treat as “source” • Maybe some benefit in looking at realistic extracted conditions? • RTML • Bunch-bunch feedback in turn-around? • Linac • Bunch compression, wakefields, pulse-pulse feedback • BDS/IR • Including beam-beam simulation for luminosity + beamstrahlung • Extraction line?

5. Simulation Tools • Many simulation tools exist and have been used in the past • placet, merlin, lucretia, bmad, ptc/madx… • Either stand-alone or joined with scripts • Having multiple codes useful (and annoying) • Have to track down difference in results, can lead to deeper understanding, helps avoid obvious mistakes… • To profit from multiple analysis efforts, useful to define some standards • Error parameter lists • Algorithms, including application specifics (e.g. method of adjusting E in DFS).

6. Work performed in the past • RTML, Linac, BDS studied separately • Independently defined luminosity growth “budgets” • Most effort on Linac emittance preservation techniques • Linac+BDS global simulation for RDR performance studies

7. ILC (RDR-era) S2E Simulations • Lucretia • Linac • Independently “static” tune 100 seeds • Pick those that fulfill “emttance growth budget” expectations. • Apply dynamic errors, tracking through to get wakefields and realistic beam response functions • Include GM & 5Hz feedbacks • BDS • Full tuning (BBA, orbit steering etc & FFS tuning with sextupoles). • Use GUINEA-PIG for beam-beam simulations, track pairs through solenoid to detector. • BDS 5Hz feedbacks • Intra-pulse effects considered separately.

8. ILC S2E Simulation Results Tuning time <1,000 pulses • ILC RDR parameters • Start-end tuning procedure • 90% seeds tune with 8% overhead • Includes pulse-pulse dynamics + FB’s • Excludes “fast effects” @ IP • Expect ~90% seeds to provide nominal luminosity • Including IP high-bandwidth feedback for worst possible conditions • Need to update for TDR parameter sets • 2-sided simulations • ILC RDR 2-sided sim: 90% seeds @ 85% lumi • Needed to expand sim time Tunable with worst-case GM, pessimistic linacbehaviour & simplistic correction techniques

10. TDR Work • Parameter sets have changed, need to refresh work. • Fully document. • Maintain as an ILC resource • Need to evaluate scope and importance taking into account available resources in immediate future. • Can image 0.5 – 2+ FTE / year in this effort.

11. TDR Work • Minimum: (< 6 months) • BDS-only “static” simulation with full error source list • All baseline parameter sets, both IR’s • 3 months • Calculate detailed jitter tolerance of final doublet magnet sets including action of intra-pulse FB • +1 month • Detailed list of well-motivated tolerances/ requirements for magnets and diagnostics • +1 month • Better: +6-12 months • Include GM + dynamics • Include Linac • Intra-pulse dynamics considerations • Include parameterised effects in S2E simulations • Best: + (?) months • Include RTML • Include DR • Multiple codes